Sensing catheters

ABSTRACT

A catheter system may include a catheter lumen, first and second electrodes, and a sensor in communication with the first and second electrodes. The sensor may be configured to detect at least one of: a bulk volume of blood within a blood vessel and extravasation of a drug from the blood vessel into soft tissue adjacent the blood vessel. Other catheter systems may include a catheter lumen and a sensing chip coupled to the catheter lumen. The sensing chip may be configured to detect at least one of: a bulk volume of blood within a blood vessel and extravasation of a drug from the blood vessel into soft tissue adjacent the blood vessel.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/912,421, filed Jun. 25, 2020, and entitled SENSING CATHETERS, whichclaims priority to U.S. Provisional Patent Application No. 62/870,253,filed Jul. 3, 2019, and entitled SENSING CATHETERS, which areincorporated herein in their entirety.

BACKGROUND

Catheters are commonly used for a variety of infusion therapies. Forexample, catheters may be used for infusing fluids, such as normalsaline solution, various medicaments, and total parenteral nutrition,into a patient. Catheters may also be used for withdrawing blood fromthe patient.

A common type of catheter is an over-the-needle peripheral intravenouscatheter (“PIVC”). As its name implies, the over-the-needle PIVC may bemounted over an introducer needle having a sharp distal tip. The PIVCand the introducer needle may be assembled so that the distal tip of theintroducer needle extends beyond the distal tip of the PIVC with thebevel of the needle facing away from skin of the patient. The PIVC andthe introducer needle are generally inserted at a shallow angle throughthe skin and into a blood vessel of the patient, such as an artery, avein, or any other vasculature of the patient.

In order to verify proper placement of the introducer needle and/or thePIVC within a blood vessel, a clinician will typically watch for blood“flashback” to occur within the PIVC. Blood flashback occurs when bloodtravels proximally between an outer surface of the introducer needle andan inner surface of the PIVC, which may be transparent. Thus, theclinician may visualize the blood and confirm placement of theintroducer needle within the vasculature. Once placement of the needlehas been confirmed, the clinician may temporarily occlude flow in thevein and remove the introducer needle, leaving the PIVC in place forfuture blood withdrawal and/or fluid infusion.

However, the blood flashback method may also result in false positivesdue to capillary blood within soft tissues surrounding the blood vessel.This capillary blood may provide a false signal to the clinician beforethe introducer needle and/or the PIVC have been properly placed withinthe blood vessel.

Moreover, once a PIVC has been placed within a blood vessel and a drugis delivered to the blood vessel via the PIVC, extravasation of the drugout of the blood vessel and into soft tissues adjacent the blood vesselmay occur. A sensor may be attached to the patient's skin close to thecatheter insertion site to monitor the patient for drug extravasationevents. However, this method of detection may only work after asignificant amount of the drug has leaked out of the catheter/bloodvessel and migrates close to the patient's skin. Moreover, a sensorplaced on the patient's skin is an additional attachment to the patient(and cost) which has to be removed and re-attached periodically (e.g.,when the patient needs to go to the bathroom).

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one example technology area where some implementationsdescribed herein may be practiced.

SUMMARY

The present disclosure relates generally to vascular access devices andrelated systems and methods.

In some embodiments, a catheter system may include a catheter, which mayinclude a catheter lumen having a proximal end, a distal end, an innerlumen surface, and an outer lumen surface. The catheter may also includefirst and second electrodes coupled to the catheter lumen. A drug sensormay also be in electrical communication with the first and secondelectrodes. The distal end of the catheter lumen may be inserted into ablood vessel of a patient such that: (1) at least a portion of the firstand second electrodes are embedded within a soft tissue of the patientadjacent the blood vessel; (2) the first and second electrodes are inelectrical communication with each other via the soft tissue of thepatient between the first and second electrodes; and (3) the drug sensordetects whether extravasation of a drug has occurred from the bloodvessel into the soft tissue of the patient by sensing an impedanceassociated with the soft tissue of the patient.

In some embodiments, the catheter system may include a first attachmentfeature configured to electrically couple the drug sensor to the firstelectrode and a second attachment feature configured to electricallycouple the drug sensor to the second electrode.

In some embodiments, the first and second electrodes may includeelectrically conductive material deposited on the outer lumen surface ofthe catheter and the first and second electrodes may be spaced apartfrom each other along the outer lumen surface of the catheter.

In some embodiments, the first electrode may include an electricallyconductive material placed within a first channel formed along thecatheter lumen, the second electrode may include an electricallyconductive material placed within a second channel formed along thecatheter lumen, and the first and second electrodes may be spaced apartfrom each other along the outer lumen surface.

In some embodiments, the first and second channels may include openchannels and distal portions of the first and second channels mayinclude electrically insulating covers configured to electricallyisolate portions of the first and second electrodes that reside withinthe blood vessel of the patient when the distal end of the catheterlumen is inserted into the blood vessel of the patient.

In some embodiments, the first and second channels may include closedchannels and the first and second channels are at least partially skivedto allow the first and second electrodes to be in electricalcommunication with each other via soft tissue between the first andsecond electrodes.

In some embodiments, the catheter system may include a third electrodeincluding an electrically conductive material placed within a thirdchannel formed along the catheter lumen and the first, second, and thirdelectrodes may be spaced apart from each other along the outer lumensurface.

In some embodiments, a catheter system may include a catheter includinga catheter lumen having a proximal end, a distal end, an inner lumensurface, and an outer lumen surface. The catheter may also include firstand second electrodes. A blood sensor may be in communication with thefirst and second electrodes. The distal end of the catheter lumen may beinserted into a blood vessel of a patient such that: (1) at least aportion of the first and second electrodes are embedded within the bloodvessel of the patient; (2) the first and second electrodes are incommunication with each other via blood residing within the blood vesselof the patient; and (3) the blood sensor detects insertion of the distalend of the catheter lumen into the blood vessel of the patient bysensing at least one characteristic associated with the blood residingwithin the blood vessel of the patient.

In some embodiments, the at least one characteristic associated with theblood residing within the blood vessel of the patient includes at leastone of: an impedance, a capacitance, a pressure, and an electromagneticsignal.

In some embodiments, the catheter system may include a first attachmentfeature configured to electrically couple the blood sensor to the firstelectrode and a second attachment feature configured to electricallycouple the blood sensor to the second electrode.

In some embodiments, the first and second electrodes include anelectrically conductive material deposited on the outer lumen surface,at least portions of the first and second electrodes are locatedproximate the distal end of the catheter lumen, and the first and secondelectrodes are spaced apart from each other on the outer lumen surfaceof the catheter lumen.

In some embodiments, the electrically conductive material includes anelectrically conductive ink.

In some embodiments, the catheter lumen is made of an electricallyconductive plastic, the catheter lumen includes the first electrode, thecatheter system further includes an introducer needle, and theintroducer needle includes the second electrode.

In some embodiments, the blood sensor is configured to detect when thedistal end of the catheter lumen is inserted into the blood vessel ofthe patient by sensing an electrical characteristic associated with theblood residing within the blood vessel of the patient between thecatheter lumen and the introducer needle.

In some embodiments, the inner lumen surface of the catheter lumenfurther includes an electrically insulating layer and the blood sensoris configured to detect when the distal end of the catheter lumen isinserted into the blood vessel of the patient by sensing an electricalcharacteristic associated with the blood residing within the bloodvessel of the patient between the distal end of the catheter lumen and adistal portion of the introducer needle.

In some embodiments, a catheter system may include a catheter includinga catheter lumen having a proximal end, a distal end, an inner lumensurface, and an outer lumen surface. The catheter may also include adrug sensing chip coupled to the catheter lumen. When the distal end ofthe catheter lumen is inserted into a blood vessel of a patient: (1) atleast a portion of the drug sensing chip may be embedded within a softtissue of the patient adjacent the blood vessel; and (2) the drugsensing chip can detect whether extravasation of a drug has occurredfrom the blood vessel into the soft tissue of the patient.

In some embodiments, the drug sensing chip is configured to detectextravasation of the drug from the blood vessel into the soft tissue ofthe patient by sensing an impedance associated with the soft tissue ofthe patient.

In some embodiments, the drug sensing chip is configured to detectextravasation of the drug from the blood vessel into the soft tissue ofthe patient by sensing at least one of: a pressure associated with thesoft tissue of the patient, a capacitance associated with the softtissue of the patient, and an infrared signal associated with the softtissue of the patient.

In some embodiments, the drug sensing chip includes an output configuredto provide an indication when extravasation of a drug from the bloodvessel into the soft tissue of the patient has been detected. In someembodiments, the output includes an LED.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the embodiments of the present disclosure, asclaimed. It should be understood that the various embodiments of thepresent disclosure are not limited to the arrangements andinstrumentality shown in the drawings. It should also be understood thatthe embodiments of the present disclosure may be combined, or that otherembodiments may be utilized and that structural changes, unless soclaimed, may be made without departing from the scope of the variousembodiments of the present disclosure. The following detaileddescription is, therefore, not to be taken in a limiting sense.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1A is an upper perspective view of an example catheter system 10,according to some embodiments;

FIG. 1B is a cross-sectional top view of the catheter system 10 of FIG.1A, according to some embodiments;

FIG. 2 is a partial cross-sectional side view of an example cathetersystem 200 inserted into tissue, according to some embodiments;

FIG. 3 is a cross-sectional side view of an example catheter system 300inserted into tissue, according to some embodiments;

FIG. 4 is a partial cross-sectional side view of an example cathetersystem 400 inserted into tissue, according to some embodiments;

FIG. 5 is a perspective side view of an example catheter 500, accordingto some embodiments;

FIG. 6 is a perspective side view of an example catheter 600, accordingto some embodiments;

FIG. 7 is a partial cross-sectional side view of an example cathetersystem 700 which includes the catheter 600 of FIG. 6 inserted intotissue, according to some embodiments; and

FIG. 8 shows an example catheter system 800 inserted into tissue,according to some embodiments.

It is to be understood that the Figures are for purposes of illustratingthe concepts of the present disclosure and may not be drawn to scale.Furthermore, the Figures illustrate exemplary embodiments and do notrepresent limitations to the scope of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of the present disclosure will be best understoodby reference to the Figures, wherein like parts are designated by likenumerals throughout. It will be readily understood that the componentsof the present disclosure, as generally described and illustrated in theFigures herein, could be arranged and designed in a wide variety ofdifferent configurations. Thus, the following more detailed descriptionof the embodiments of the apparatus, systems, and methods, asrepresented in the Figures, is not intended to limit the scope of thepresent disclosure, as claimed in this or any other application claimingpriority to this application, but is merely representative of exemplaryembodiments of the present disclosure.

Referring to FIGS. 1A and 1B, in some embodiments, a catheter system 10may include a needle assembly 12 and a catheter assembly 14. FIGS. 1Aand 1B illustrate the catheter system 10 in an insertion position, readyfor insertion into a vein of a patient (not shown), according to someembodiments. In some embodiments, the catheter assembly 14 may include acatheter adapter 16, which may include a distal end 18, a proximal end20, and a catheter assembly lumen 21 extending through the distal end 18and the proximal end 20. In some embodiments, the catheter assembly 14may include a catheter 22, which may include a distal end 24 and aproximal end 26. In some embodiments, the catheter 22 may include aperipheral intravenous catheter (“PIVC”). In some embodiments, theproximal end 26 of the catheter 22 may be secured within the catheteradapter 16.

In some embodiments, the needle assembly 12 may include a needle hub 28,which may be removably coupled to the catheter adapter 16. In someembodiments, the needle assembly 12 may include an introducer needle 30.In some embodiments, a proximal end of the introducer needle 30 may besecured within the needle hub 28. In some embodiments, the introducerneedle 30 may extend through the catheter 22 when the catheter system 10is in an insertion position ready for insertion into the vein of apatient, as illustrated, for example, in FIGS. 1A and 1B.

In some embodiments, the needle assembly 12 may include a needle grip32, which a clinician may grip and move proximally to withdraw theintroducer needle 30 from the vein once placement of the catheter 22within the vein is confirmed. In some embodiments, the catheter system10 may include an extension tube 34. In some embodiments, a distal endof the extension tube 34 may be coupled the catheter adapter 16 and aproximal end of the extension tube 34 may be coupled to an adapter 36.

In some embodiments, a fluid infusion device (not shown) may be coupledto the adapter 36 to deliver fluid to the patient via the catheter 22inserted in the vein, once the introducer needle 30 is removed from thecatheter system 10. In some embodiments, a blood collection device (notshown) may be coupled to the adapter 36 to withdraw blood from thepatient via the catheter 22 inserted in the vein.

In some embodiments, the catheter system 10 may be integrated, havingthe extension tube 34 integrated within the catheter adapter 16, suchas, for example, the BD NEXIVA™ Closed IV Catheter System, the BDNEXIVA™ DIFFUSICS™ Closed IV Catheter System, the BD PEGASUS™ SafetyClosed IV Catheter System, or another integrated catheter system. Anexample of an integrated catheter system 10 is illustrated in FIGS. 1Aand 1B. In some embodiments, the catheter system 10 may benon-integrated, without the extension tube 34.

In some embodiments, the catheter system 10 may be vented to observeblood and facilitate proximal flow of blood within the introducer needle30 and/or the catheter 22. In some embodiments, the catheter system 10may be vented in any suitable manner. For example, a vent plug 38 may becoupled to the adapter 36 during insertion of the catheter assembly 14into the patient. In some embodiments, the vent plug 38 may be permeableto air but not to blood. In some embodiments, the catheter 22, thecatheter adapter 16, the extension tube 34, the adapter 36, and the ventplug 38 may be in fluid communication. As another example, in someembodiments, the needle hub 28 may include a flash chamber.

FIG. 2 illustrates a partial cross-sectional side view of an examplecatheter system 200 inserted into soft tissue, according to someembodiments. The catheter system 200 may generally include a catheter223, a catheter adapter 216, an introducer needle 230, and a sensor 250.As shown in FIG. 2 , the catheter 223 may be inserted through the skin81 and into the soft tissue 80, until a distal portion of the catheter223 enters a blood vessel 70.

The catheter 223 may include a catheter lumen 222 having a proximal end226, a distal end 224, an inner lumen surface 225, and an outer lumensurface 227. Although not shown in FIG. 2 , in some embodiments, thedistal end 224 of the catheter 223 may also be tapered, similar to thetapered distal end 24 of the catheter 22 illustrated in FIGS. 1A and 1B.

The catheter system 200 may also include a first electrode 241 and asecond electrode 242. In the embodiment shown in FIG. 2 , the first andsecond electrodes 241, 242 may be coupled to the outer lumen surface 227of the catheter 223, extending along a length of the catheter 223.However, it will also be understood that in other embodiments (notshown), the first and second electrodes 241, 242 may alternatively, orin addition thereto, be coupled to the inner lumen surface 225 of thecatheter 223. The first and second electrodes 241, 242 may also bespaced apart from each other along the outer lumen surface 227 and/oralong the inner lumen surface 225. In some embodiments, at least aportion of the first electrode 241 and a portion of the second electrode242 may be located proximate the distal end 224 of the catheter 223. Insome embodiments, the portions of the first and second electrodes 241,242 located proximate the distal end 224 of the catheter 223 may extendtoward each other to create an electrode gap 243 proximate the distalend 224 of the catheter 223. In some embodiments, an orientation,direction, or distance of the electrode gap 243 may vary. In someembodiments, the first and second electrodes 241, 242 may include anelectrically conductive material deposited on a surface of the catheter223, such as the outer lumen surface 227 and/or the inner lumen surface225. In some embodiments, the electrically conductive material mayinclude an electrically conductive ink.

The catheter system 200 may also include a first attachment feature 291configured to couple the first electrode 241 to the sensor 250, and asecond attachment feature 292 configured to couple the second electrode242 to the sensor 250. The first and second attachment features 291, 292may be coupled to, and/or integrated with, the catheter adapter 216.However, in other embodiments (not shown), the first and secondattachment features 291, 292 may be directly coupled to, and/orintegrated with, the catheter 223. In some embodiments, the first andsecond attachment features 291, 292 may traverse between an outersurface of the catheter adapter 216 and an inner surface of the catheteradapter 216. In some embodiments, the first attachment feature 291 maydirectly, or indirectly, contact the first electrode 241, and the secondattachment feature 292 may directly, or indirectly, contact the secondelectrode 242. In some embodiments, the first and second attachmentfeatures 291, 292 may be configured to electrically couple the first andsecond electrodes 241, 242 to the sensor 250.

In some embodiments, the sensor 250 may be a blood sensor 250 configuredto sense a bulk volume of blood within the blood vessel 70. In thismanner, the blood sensor 250 may detect when the distal end 224 of thecatheter 223 has been successfully inserted into the blood vessel 70,and an indication of successful insertion may be provided to theclinician via any suitable output device known in the art. For example,a bulk volume of blood within the blood vessel 70 can exhibit differentelectrical, chemical, and/or physical characteristics in comparison tocapillary blood dispersed within the soft tissue 80 adjacent the bloodvessel 70. These differences in electrical, chemical, and/or physicalcharacteristics may be utilized to indicate whether or not the catheter223 has been properly inserted within the blood vessel 70 in order toachieve less false positives indicating a successful insertion, incomparison to utilizing the blood flashback method alone.

In some embodiments, the blood sensor 250 may be in communication withthe first and second electrodes 241, 242 such that, when the distal end224 of the catheter lumen 222 is successfully inserted into the bloodvessel 70: (1) at least a portion of the first and second electrodes241, 242 are embedded within the blood vessel 70; (2) the first andsecond electrodes 241, 242 are in communication with each other viablood residing within the blood vessel 70; and (3) the blood sensor 250detects successful insertion of the distal end 224 of the catheter lumen222 within the blood vessel 70 by sensing at least one characteristicassociated with the blood residing within the blood vessel 70.

In some embodiments, the at least one characteristic associated with theblood residing within the blood vessel 70 includes at least one of: animpedance, a capacitance, a conductance, an inductance, anelectromagnetic signal, a pressure, and a temperature. In someembodiments, the at least one characteristic may be measured directly,or indirectly. In some embodiments, determination of successfulinsertion may be based on a threshold value associated with the at leastone characteristic, a change detected in the at least one characteristicas the distal end 224 of the catheter lumen 222 is inserted into theblood vessel 70, and/or a relative difference that is detected in the atleast one characteristic as the distal end 224 of the catheter lumen 222is inserted into the blood vessel 70.

FIG. 3 illustrates a cross-sectional side view of an example cathetersystem 300 inserted into soft tissue 80, according to some embodiments.The catheter system 300 may generally include a catheter 323, a catheteradapter 316, an introducer needle 330, and a sensor 350. As shown inFIG. 3 , the catheter 323 may be inserted through the skin 81 and intothe soft tissue 80, until a distal portion of the catheter 323 entersthe blood vessel 70.

The catheter 323 may include a catheter lumen 322 having a proximal end326, a distal end 324, an inner lumen surface 325, and an outer lumensurface 327. Although not shown in FIG. 3 , in some embodiments, thedistal end 324 of the catheter 323 may also be tapered, similar to thetapered distal end 24 of the catheter 22 illustrated in FIGS. 1A and 1B.

The catheter system 300 may also include a first electrode 341 and asecond electrode 342. In the embodiment shown in FIG. 3 , the catheterlumen 322 may include the first electrode 341, and the introducer needle330 may include the second electrode 342. For example, in someembodiments, the catheter lumen 322 may be made of an electricallyconductive material. In some embodiments, the electrically conductivematerial of the catheter lumen 322 may include an electricallyconductive plastic. In some embodiments, the catheter lumen 322 may alsoinclude a radiopaque material. Additionally, in some embodiments, theintroducer needle 330 may include an electrically conductive material.In some embodiments, the electrically conductive material of theintroducer needle 330 may include an electrically conductive metal. Insome embodiments, at least a portion of the first electrode 341 and aportion of the second electrode 342 may be located proximate the distalend 324 of the catheter 323.

In some embodiments, the inner lumen surface 325 of the catheter lumen322 may include an electrically insulating layer 329 or material. Thiselectrically insulating layer 329 may be configured to electricallyinsulate the first electrode 341 (e.g., the catheter 323) from thesecond electrode 342 (e.g., the introducer needle 330). In someembodiments, the electrically insulating layer 329 may be coupled to theinner lumen surface 325 of the catheter lumen 322 via a coating process.In some embodiments, the electrically insulating layer 329 may beintegrated with the catheter 323 via a co-extrusion process.

The catheter system 300 may also include a first attachment feature 391configured to couple the first electrode 341 to the sensor 350, and asecond attachment feature 392 configured to couple the second electrode342 to the sensor 350. The first and second attachment features 391, 392may be coupled to, and/or integrated with, the catheter adapter 316,and/or a needle assembly/hub (not shown in FIG. 3 ). However, in otherembodiments (not shown), the first and second attachment features 391,392 may be directly coupled to, and/or integrated with, the catheter 323and the introducer needle 330. In some embodiments, the first and secondattachment features 391, 392 may traverse between an outer surface ofthe catheter adapter 316 (and/or a needle assembly/hub) and an innersurface of the catheter adapter 316 (and/or a needle assembly/hub). Insome embodiments, the first attachment feature 391 may directly, orindirectly, contact the first electrode 341, and the second attachmentfeature 392 may directly, or indirectly, contact the second electrode342. In some embodiments, the first and second attachment features 391,392 may be configured to electrically couple the first and secondelectrodes 341, 342 to the sensor 350.

In some embodiments, the sensor 350 may be a blood sensor 350 configuredto sense a bulk volume of blood within the blood vessel 70. In thismanner, the blood sensor 350 may detect when the distal end 324 of thecatheter 323 has been successfully inserted into the blood vessel 70,and an indication of successful insertion may be provided to theclinician via any suitable output device known in the art. As previouslydiscussed, a bulk volume of blood within the blood vessel 70 can exhibitdifferent electrical, chemical, and/or physical characteristics incomparison to capillary blood dispersed within the soft tissue 80adjacent the blood vessel 70. These differences in electrical, chemical,and/or physical characteristics may be utilized to indicate whether ornot the catheter 323 has been properly inserted within the blood vessel70 in order to achieve less false positives of indicating a successfulinsertion, in comparison to utilizing the blood flashback method alone.

In some embodiments, the blood sensor 350 may be in communication withthe first and second electrodes 341, 342 such that, when the distal end324 of the catheter lumen 322 is successfully inserted into the bloodvessel 70: (1) at least a portion of the first and second electrodes341, 342 are embedded within the blood vessel 70; (2) the first andsecond electrodes 341, 342 are in communication with each other viablood residing within the blood vessel 70; and (3) the blood sensor 350detects successful insertion of the distal end 324 of the catheter lumen322 into the blood vessel 70 by sensing at least one characteristicassociated with the blood residing within the blood vessel 70.

In some embodiments, the at least one characteristic associated with theblood residing within the blood vessel 70 includes at least one of: animpedance, a capacitance, a conductance, an inductance, anelectromagnetic signal, a pressure, and a temperature. In someembodiments, the at least one characteristic may be measured directly,or indirectly. In some embodiments, determination of successfulinsertion may be based on a threshold value associated with the at leastone characteristic, a change detected in the at least one characteristicas the distal end 324 of the catheter lumen 322 is inserted into theblood vessel 70, and/or a relative difference that is detected in the atleast one characteristic as the distal end 324 of the catheter lumen 322is inserted into the blood vessel 70.

In some embodiments, the blood sensor 350 is configured to detect whenthe distal end of the catheter lumen 322 is inserted into the bloodvessel 70 by sensing an electrical characteristic associated with theblood residing within the blood vessel 70 between the catheter lumen 322and the introducer needle 330.

In some embodiments, the blood sensor 350 is configured to detect whenthe distal end 324 of the catheter lumen 322 is inserted into the bloodvessel 70 by sensing an electrical characteristic associated with theblood residing within the blood vessel 70 between the distal end 324 ofthe catheter lumen 322 and a distal portion of the introducer needle330.

FIG. 4 illustrates a partial cross-sectional side view of an examplecatheter system 400 inserted into soft tissue, according to someembodiments. The catheter system 400 may generally include a catheter423, a catheter adapter 416, and a sensor 460. As shown in FIG. 4 , thecatheter 423 may be inserted through the skin 81 and into the softtissue 80 until a distal portion of the catheter 423 enters the bloodvessel 70.

The catheter 423 may include a catheter lumen 422 having a proximal end426, a distal end 424, an inner lumen surface 425, and an outer lumensurface 427. Although not shown in FIG. 4 , in some embodiments, thedistal end 424 of the catheter 423 may also be tapered, similar to thetapered distal end 24 of the catheter 22 illustrated in FIGS. 1A and 1B.

The catheter system 400 may also include a first electrode 441 and asecond electrode 442. In the embodiment shown in FIG. 4 , the first andsecond electrodes 441, 442 may be coupled to the outer lumen surface 427of the catheter 423, extending along a length of the catheter 423.However, it will also be understood that in other embodiments (notshown), the first and second electrodes 441, 442 may alternatively, orin addition thereto, be coupled to the inner lumen surface 425 of thecatheter 423. The first and second electrodes 441, 442 may also bespaced apart from each other along the outer lumen surface 427 and/oralong the inner lumen surface 425 at one or more distances.

In some embodiments, at least a portion of the first electrode 441 and aportion of the second electrode 442 may be embedded within the softtissue 80 adjacent the blood vessel 70 when the distal end 424 of thecatheter lumen 422 is inserted into the blood vessel 70. In someembodiments, portions of the first and second electrodes 441, 442 mayextend toward each other to create an electrode gap 443 locatedintermediate the proximal and distal ends 426, 424 of the catheter 423.In some embodiments, an orientation, direction, or distance of theelectrode gap 443 may vary. In some embodiments, the first and secondelectrodes 441, 442 may include an electrically conductive materialdeposited on a surface of the catheter 423, such as the outer lumensurface 427 and/or the inner lumen surface 425. In some embodiments, theelectrically conductive material may include an electrically conductiveink.

The catheter system 400 may also include a first attachment feature 491configured to couple the first electrode 441 to the sensor 460, and asecond attachment feature 492 configured to couple the second electrode442 to the sensor 460. The first and second attachment features 491, 492may be coupled to, and/or integrated with, the catheter adapter 416.However, in other embodiments (not shown), the first and secondattachment features 491, 492 may be directly coupled to, and/orintegrated with, the catheter 423. In some embodiments, the first andsecond attachment features 491, 492 may traverse between an outersurface of the catheter adapter 416 and an inner surface of the catheteradapter 416. In some embodiments, the first attachment feature 491 maydirectly, or indirectly, contact the first electrode 441, and the secondattachment feature 492 may directly, or indirectly, contact the secondelectrode 442. In some embodiments, the first and second attachmentfeatures 491, 492 may be configured to electrically couple the first andsecond electrodes 441, 442 to the sensor 460.

In some embodiments, the sensor 460 may be a drug sensor 460 configuredto sense when a drug 85 has leaked out of the blood vessel 70 and intothe soft tissue 80 adjacent the blood vessel 70 via an extravasationprocess. In this manner, the drug sensor 460 may detect whenextravasation of the drug 85 has occurred and an indication of drugextravasation may be provided to the clinician via any suitable outputdevice known in the art. For example, soft tissue containing anextravasated drug can exhibit different electrical, chemical, and/orphysical characteristics in comparison to soft tissue that does notcontain an extravasated drug. These differences in electrical, chemical,and/or physical characteristics may be utilized to indicate whether ornot the soft tissue contains an extravasated drug in order to alert theclinician to a possible dangerous situation.

In some embodiments, the drug sensor 460 may be in communication withthe first and second electrodes 441, 442 coupled to the catheter lumen422 such that, when the distal end 424 of the catheter lumen 422 issuccessfully inserted into the blood vessel 70: (1) at least a portionof the first and second electrodes 441, 442 are embedded within the softtissue 80 adjacent the blood vessel 70; (2) the first and secondelectrodes 441, 442 are in communication with each other through thesoft tissue 80 between the first and second electrodes 441, 442; and (3)the drug sensor 460 detects whether extravasation of the drug 85 hasoccurred from the blood vessel 70 into the soft tissue 80 by sensing acharacteristic associated with the soft tissue 80.

In some embodiments, the at least one characteristic associated with thesoft tissue 80 containing the extravasated drug 85 includes at least oneof: an impedance, a capacitance, a conductance, an inductance, anelectromagnetic signal, a pressure, and a temperature. In someembodiments, the at least one characteristic may be measured directly,or indirectly. In some embodiments, determination of drug 85extravasation may be based on a threshold value associated with the atleast one characteristic, a change detected in the at least onecharacteristic as the soft tissue 80 becomes infused with the drug 85,and/or a relative difference that is detected in the at least onecharacteristic as the soft tissue 80 becomes infused with the drug 85.

FIG. 5 illustrates a perspective side view of an example catheter 500which may be utilized to detect drug extravasation, according to someembodiments. The catheter 500 may include a catheter lumen 522 having aproximal end 526, a distal end 524, an inner lumen surface 525, and anouter lumen surface 527. Although not shown in FIG. 5 , in someembodiments, the distal end 524 of the catheter 500 may also be tapered,similar to the tapered distal end 24 of the catheter 22 illustrated inFIGS. 1A and 1B.

The catheter 500 may include a first electrode 541, a second electrode542, and a third electrode 543. However, in other embodiments (notshown), the catheter 500 may only include two electrodes. In still otherembodiments (not shown), the catheter 500 may include more than threeelectrodes.

In some embodiments, the first, second, and third electrodes 541, 542,543 may include an electrically conductive material. In someembodiments, the electrically conductive material may include anelectrically conductive metal. The first, second, and third electrodes541, 542, 543 may also be spaced apart from each other along thecatheter 500 and/or the outer lumen surface 527.

In the embodiment shown in FIG. 5 , the first, second, and thirdelectrodes 541, 542, 543 may each be coupled to the catheter within afirst channel 561, a second channel 562, and a third channel 563,respectively. The first, second, and third channels 561, 562, 563 mayalso extend along a length of the catheter 500. The first, second, andthird channels 561, 562, 563 may include closed channels formed withinthe body of the catheter lumen 522 in order to electrically insulate thefirst, second, and third electrodes 541, 542, 543 from each other.

The first, second, and third electrodes/channels 541, 542, 543, 561,562, 563 may be formed by co-extruding the first, second, and thirdelectrodes 541, 542, 543 with the catheter 500. In some embodiments, thefirst, second, and third channels 561, 562, 563 may then undergo askiving process to expose portions of the first, second, and thirdelectrodes 541, 542, 543. This skiving process may include removingcatheter material that is above the first, second, and third electrodes541, 542, 543 to expose them and allow the first, second, and thirdelectrodes 541, 542, 543 to be in electrical communication with eachother via soft tissue 80 between the first, second, and third electrodes541, 542, 543. In some embodiments, a distal portion of the catheter 500may not be skived, in order to keep the first, second, and thirdelectrodes 541, 542, 543 electrically isolated from each other at thedistal portion of the catheter 500. In this manner, the first, second,and third electrodes 541, 542, 543 at the distal portion of the catheter500 (which enters into a blood vessel) will not sense a drug within theblood vessel and produce a false positive indication for drugextravasation.

FIG. 6 illustrates a perspective side view of an example catheter 600which may be utilized to detect drug extravasation, according to someembodiments. The catheter 600 may include a catheter lumen 622 having aproximal end 626, a distal end 624, an inner lumen surface 625, and anouter lumen surface 627. Although not shown in FIG. 6 , in someembodiments, the distal end 624 of the catheter 600 may also be tapered,similar to the tapered distal end 24 of the catheter 22 illustrated inFIGS. 1A and 1B.

The catheter 600 may include a first electrode 641, a second electrode642, and a third electrode 643. However, in other embodiments (notshown), the catheter 600 may only include two electrodes. In still otherembodiments (not shown), the catheter 600 may include more than threeelectrodes.

In some embodiments, the first, second, and third electrodes 641, 642,643 may include an electrically conductive material. In someembodiments, the electrically conductive material may include anelectrically conductive metal. The first, second, and third electrodes641, 642, 643 may also be spaced apart from each other along thecatheter 600 and/or the outer lumen surface 627 at any distance.

In the embodiment shown in FIG. 6 , the first, second, and thirdelectrodes 641, 642, 643 may each be coupled to the catheter within afirst channel 661, a second channel 662, and a third channel 663,respectively. The first, second, and third channels 661, 662, 663 maylikewise extend along a length of the catheter 600. The first, second,and third channels 661, 662, 663 may include open channels formed withinthe body of the catheter lumen 622 that are open to the outer lumensurface 627 in order to allow electrical communication between thefirst, second, and third electrodes 641, 642, 643 via soft tissues thatare between the first, second, and third electrodes 641, 642, 643.

The first, second, and third electrodes/channels 641, 642, 643, 661,662, 663 may be also be formed via a co-extrusion process, or by anyother suitable manufacturing process. In some embodiments, distalportions of the first, second, and third electrodes 641, 642, 643 may beelectrically insulated from each other by a cover, a coating, a sleeve,or a cap. For example, in some embodiments, a cover 665 may be coupledto the distal end 624 of the catheter 600. The cover 665 may beconfigured to electrically isolate portions of the first, second, andthird electrodes 641, 642, 643 from each other, which reside within ablood vessel. In this manner, the first, second, and third electrodes641, 642, 643 at the distal portion of the catheter 600 (which may enterinto a blood vessel) will not sense a drug within the blood vessel andproduce a false positive indication of drug extravasation.

FIG. 7 is a partial cross-sectional side view of an example cathetersystem 700 including the catheter 600 of FIG. 6 inserted into tissue,according to some embodiments. The catheter system 700 may generallyinclude the catheter 600, a catheter adapter 716, and a sensor 760. Asshown in FIG. 7 , the catheter 600 may be inserted through the skin 81and into the soft tissue 80 until a distal portion of the catheter 600enters the blood vessel 70.

The catheter system 700 may also include a first attachment feature 791configured to couple the first electrode 641 to the sensor 760, and asecond attachment feature 792 configured to couple the second electrode642 to the sensor 760. The first and second attachment features 791, 792may be coupled to, and/or integrated with, the catheter adapter 716.However, in other embodiments (not shown), the first and secondattachment features 791, 792 may be directly coupled to, and/orintegrated with, the catheter 600. In some embodiments, the first andsecond attachment features 791, 792 may traverse between an outersurface of the catheter adapter 716 and an inner surface of the catheteradapter 716. In some embodiments, the first attachment feature 791 maydirectly, or indirectly, contact the first electrode 641, and the secondattachment feature 792 may directly, or indirectly, contact the secondelectrode 642. In some embodiments, the first and second attachmentfeatures 791, 792 may be configured to electrically couple the first andsecond electrodes 641, 642 to the sensor 760.

In some embodiments, the sensor 760 may be a drug sensor 760 configuredto sense when a drug 85 has leaked out of the blood vessel 70 and intothe soft tissue 80 adjacent the blood vessel 70 via an extravasationprocess. In this manner, the drug sensor 760 may detect whenextravasation of the drug 85 has occurred and an indication of drugextravasation may be provided to the clinician via any suitable outputdevice known in the art. As previously discussed, soft tissue containingan extravasated drug can exhibit different electrical, chemical, and/orphysical characteristics in comparison to soft tissue that does notcontain an extravasated drug. These differences in electrical, chemical,and/or physical characteristics may be utilized to indicate whether ornot the soft tissue contains an extravasated drug in order to alert theclinician to a possible dangerous situation.

In some embodiments, the drug sensor 760 may be in communication withthe first and second electrodes 641, 642 such that, when the distal end624 of the catheter lumen 622 is successfully inserted into the bloodvessel 70: (1) at least a portion of the first and second electrodes641, 642 are embedded within the soft tissue 80 adjacent the bloodvessel 70; (2) the first and second electrodes 641, 642 are incommunication with each other through the soft tissue 80 between thefirst and second electrodes 641, 642; and (3) the drug sensor 760detects whether extravasation of the drug 85 has occurred from the bloodvessel 70 into the soft tissue 80 by sensing a characteristic associatedwith the soft tissue 80.

In some embodiments, the at least one characteristic associated with thesoft tissue 80 containing the extravasated drug 85 includes at least oneof: an impedance, a capacitance, a conductance, an inductance, anelectromagnetic signal, a pressure, and a temperature. In someembodiments, the at least one characteristic may be measured directly,or indirectly. In some embodiments, determination of drug 85extravasation may be based on a threshold value associated with the atleast one characteristic, a change detected in the at least onecharacteristic as the soft tissue 80 becomes infused with the drug 85,and/or a relative difference that is detected in the at least onecharacteristic as the soft tissue 80 becomes infused with the drug 85.

FIG. 8 shows an example catheter system 800 inserted into tissue,according to some embodiments. The catheter system 800 may generallyinclude a catheter 823 and a sensor 860. As shown in FIG. 8 , thecatheter 823 may be inserted through the skin 81 and into the softtissue 80 until a distal portion of the catheter 823 enters the bloodvessel 70.

The catheter 823 may include a catheter lumen 822 having a proximal end826, a distal end 824, an inner lumen surface 825, and an outer lumensurface 827. Although not shown in FIG. 8 , in some embodiments, thedistal end 824 of the catheter 823 may also be tapered, similar to thetapered distal end 24 of the catheter 22 illustrated in FIGS. 1A and 1B.

In some embodiments, the sensor 860 may include a drug sensing chip 860coupled to the outer lumen surface 827. The drug sensing chip 860 mayinclude one or more sensors and/or one or more electrodes (not shown)arranged along its surface, which can be spaced apart from each other atone or more distances.

In some embodiments, at least a portion of the drug sensing chip 860 maybe embedded within the soft tissue 80 adjacent to the blood vessel 70when the distal end 824 of the catheter lumen 822 is inserted into theblood vessel 70. In this manner, the drug sensing chip 860 may detectwhen extravasation of a drug 85 has occurred from the blood vessel 70and into the soft tissue 80 by sensing a characteristic associated withthe soft tissue 80. If extravasation of a drug 85 has been detected, anindication of the drug extravasation event may be provided to theclinician via any suitable output device that is known in the art. Insome embodiments, the output device may include an LED light 868 thatmay be configured to indicate the presence and/or absence of a drug 85that has extravasated into the soft tissue 80.

As previously discussed, if the soft tissue 80 proximate the drugsensing chip 860 contains an extravasated drug 85, the soft tissue 80can exhibit different electrical, chemical, and/or physicalcharacteristics in comparison to soft tissue that is drug free. Thesedifferences in electrical, chemical, and/or physical characteristics maybe utilized to determine whether or not the soft tissue 80 contains anextravasated drug 85 in order to alert the clinician to a possibledangerous situation.

In some embodiments, the at least one characteristic associated with thesoft tissue 80 containing the extravasated drug 85 includes at least oneof: an impedance, a capacitance, a conductance, an inductance, anelectromagnetic signal (e.g., an infrared signal), a pressure, and atemperature. In some embodiments, the at least one characteristic may bemeasured directly, or indirectly. In some embodiments, determination ofdrug 85 extravasation may be based on a threshold value associated withthe at least one characteristic, a change detected in the at least onecharacteristic as the soft tissue 80 becomes infused with the drug 85,and/or a relative difference that is detected in the at least onecharacteristic as the soft tissue 80 becomes infused with the drug 85.

It is to be understood that any of the embodiments of the presentdisclosure may be combined together in any number of different ways. Asone non-limiting example, the embodiment of FIG. 2 may be combined withany one of (or any combination of) the embodiments of FIGS. 1A-1B and3-8 . As another non-limiting example, the embodiment of FIG. 3 may becombined with any one of (or any combination of) the embodiments ofFIGS. 1A-2 and 4-8 , and so forth.

Reference throughout this specification to “an embodiment” or “theembodiment” means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, Figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim requiresmore features than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.Thus, the claims following this Detailed Description are herebyexpressly incorporated into this Detailed Description, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements recited inmeans-plus-function format are intended to be construed in accordancewith 35 U.S.C. § 112 Para. 6. It will be apparent to those having skillin the art that changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples set forth herein.

Standard medical directions, planes of reference, and descriptiveterminology are employed in this specification. For example, anteriormeans toward the front of the body. Posterior means toward the back ofthe body. Superior means toward the head. Inferior means toward thefeet. Medial means toward the midline of the body. Lateral means awayfrom the midline of the body. Axial means toward a central axis of thebody. Abaxial means away from a central axis of the body. Ipsilateralmeans on the same side of the body. Contralateral means on the oppositeside of the body. A sagittal plane divides a body into right and leftportions. A midsagittal plane divides the body into bilaterallysymmetric right and left halves. A coronal plane divides a body intoanterior and posterior portions. A transverse plane divides a body intosuperior and inferior portions. These descriptive terms may be appliedto an animate or inanimate body.

The phrases “connected to,” “coupled to,” “engaged with,” and “incommunication with” refer to any form of interaction between two or moreentities, including mechanical, electrical, magnetic, electromagnetic,fluid, and thermal interaction. Two components may be functionallycoupled to each other even though they are not in direct contact witheach other. The term “abutting” refers to items that are in directphysical contact with each other, although the items may not necessarilybe attached together. The phrase “fluid communication” refers to twofeatures that are connected such that a fluid within one feature is ableto pass into the other feature.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. While the various aspects of theembodiments are presented in the Figures, the Figures are notnecessarily drawn to scale unless specifically indicated.

While specific embodiments and applications of the present disclosurehave been illustrated and described, it is to be understood that thescope of the appended claims is not limited to the precise configurationand components disclosed herein. Various modifications, changes, andvariations which will be apparent to those skilled in the art may bemade in the arrangement, operation, and details of the apparatus,systems, and methods disclosed herein.

All examples and conditional language recited herein are intended forpedagogical objects to aid the reader in understanding the invention andthe concepts contributed by the inventor to furthering the art, and areto be construed as being without limitation to such specifically recitedexamples and conditions. Although embodiments of the present disclosurehave been described in detail, it should be understood that the variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the present disclosure.

1. A catheter system comprising: a catheter, the catheter comprising: acatheter lumen comprising: a proximal end; a distal end; an inner lumensurface; and an outer lumen surface; and a first electrode coupled tothe catheter lumen; and a second electrode coupled to the catheterlumen; and a drug sensor in communication with the first and secondelectrodes coupled to the catheter lumen, wherein when the distal end ofthe catheter lumen is inserted into a blood vessel of a patient: atleast a portion of the first and second electrodes are embedded within asoft tissue of the patient adjacent the blood vessel, the first andsecond electrodes are in communication with each other through the softtissue of the patient between the first and second electrodes, and thedrug sensor detects whether extravasation of a drug has occurred fromthe blood vessel into the soft tissue of the patient by sensing acharacteristic associated with the soft tissue of the patient, thecharacteristic comprising at least one of inductance, impedance, andcapacitance.
 2. The catheter system of claim 1, further comprising: afirst attachment feature configured to electrically couple the drugsensor to the first electrode; and a second attachment featureconfigured to electrically couple the drug sensor to the secondelectrode.
 3. The catheter system of claim 1, wherein: the firstelectrode comprises an electrically conductive material deposited on theouter lumen surface; and the second electrode comprises an electricallyconductive material deposited on the outer lumen surface, wherein thefirst and second electrodes are spaced apart from each other along theouter lumen surface.
 4. The catheter system of claim 1, wherein: thefirst electrode comprises an electrically conductive material placedwithin a first channel formed along the catheter lumen; and the secondelectrode comprises an electrically conductive material placed within asecond channel formed along the catheter lumen, wherein the first andsecond electrodes are spaced apart from each other along the outer lumensurface.
 5. The catheter system of claim 4, wherein: the first andsecond channels comprise open channels; and distal portions of the firstand second channels are electrically insulated by a cover configured toelectrically isolate portions of the first and second electrodes thatreside within the blood vessel of the patient when the distal end of thecatheter lumen is inserted into the blood vessel of the patient.
 6. Thecatheter system of claim 4, wherein: the first and second channelscomprise closed channels; and the first and second channels are at leastpartially skived to allow the first and second electrodes to be inelectrical communication with each other via soft tissue between thefirst and second electrodes.
 7. The catheter system of claim 4, furthercomprising: a third electrode comprising an electrically conductivematerial placed within a third channel formed along the catheter lumen,wherein the first, second, and third electrodes are spaced apart fromeach other along the outer lumen surface.
 8. A catheter systemcomprising: a catheter, the catheter comprising: a catheter lumencomprising: a proximal end; a distal end; an inner lumen surface; and anouter lumen surface; and a first electrode; a second electrode; and ablood sensor in communication with the first and second electrodes,wherein when the distal end of the catheter lumen is inserted into ablood vessel of a patient: at least a portion of the first and secondelectrodes are embedded within the blood vessel of the patient, thefirst and second electrodes are in communication with each other viablood residing within the blood vessel of the patient, and the bloodsensor detects insertion of the distal end of the catheter lumen intothe blood vessel of the patient by sensing at least one characteristicassociated with the blood residing within the blood vessel of thepatient.
 9. The catheter system of claim 8, wherein the at least onecharacteristic associated with the blood residing within the bloodvessel of the patient comprises at least one of: an impedance; aninductance; a capacitance; a pressure; and an electromagnetic signal.10. The catheter system of claim 8, further comprising: a firstattachment feature configured to couple the blood sensor to the firstelectrode; and a second attachment feature configured to couple theblood sensor to the second electrode.
 11. The catheter system of claim8, wherein: the first electrode comprises an electrically conductivematerial deposited on the outer lumen surface; and the second electrodecomprises an electrically conductive material deposited on the outerlumen surface, wherein at least portions of the first and secondelectrodes are located proximate the distal end of the catheter lumen,and the first and second electrodes are spaced apart from each other onthe outer lumen surface.
 12. The catheter system of claim 11, whereinthe electrically conductive material comprises an electricallyconductive ink.
 13. The catheter system of claim 8, wherein: thecatheter lumen is made of an electrically conductive plastic; thecatheter lumen comprises the first electrode; the catheter systemfurther comprises an introducer needle; and the introducer needlecomprises the second electrode.
 14. The catheter system of claim 13,wherein the blood sensor is configured to detect when the distal end ofthe catheter lumen is inserted into the blood vessel of the patient bysensing an electrical characteristic associated with the blood residingwithin the blood vessel of the patient between the catheter lumen andthe introducer needle.
 15. The catheter system of claim 14, wherein: theinner lumen surface of the catheter lumen further comprises anelectrically insulating layer; and the blood sensor is configured todetect when the distal end of the catheter lumen is inserted into theblood vessel of the patient by sensing an electrical characteristicassociated with the blood residing within the blood vessel of thepatient between the distal end of the catheter lumen and a distalportion of the introducer needle.
 16. A catheter system comprising: acatheter, the catheter comprising: a catheter lumen comprising: aproximal end; a distal end; an inner lumen surface; and an outer lumensurface; and a drug sensing chip coupled to the catheter lumen, whereinwhen the distal end of the catheter lumen is inserted into a bloodvessel of a patient: at least a portion of the drug sensing chip isembedded within a soft tissue of the patient adjacent the blood vessel,and the drug sensing chip detects whether extravasation of a drug hasoccurred from the blood vessel into the soft tissue of the patient bysensing a characteristic associated with the soft tissue.
 17. Thecatheter system of claim 16, wherein the drug sensing chip is configuredto detect extravasation of the drug from the blood vessel into the softtissue of the patient by sensing an impedance associated with the softtissue of the patient.
 18. The catheter system of claim 16, wherein thedrug sensing chip is configured to detect extravasation of the drug fromthe blood vessel into the soft tissue of the patient by sensing at leastone of: a pressure associated with the soft tissue of the patient; aninductance associated with the soft tissue of the patient; an impedanceassociated with the soft tissue of the patient; a capacitance associatedwith the soft tissue of the patient; and an infrared signal associatedwith the soft tissue of the patient.
 19. The catheter system of claim16, wherein the drug sensing chip comprises an output device configuredto provide an indication when extravasation of a drug from the bloodvessel into the soft tissue of the patient has been detected.
 20. Thecatheter system of claim 19, wherein the output device comprises an LED.